What Richard Nixon knew about Watergate: forensic experts investigate

Forensic investigators have been called in to solve one of the greatest mysteries of US presidential history by discovering what exactly Richard Nixon knew about the Watergate break-in.

President Richard M. Nixon points to the transcripts of the White House tapesPhoto: AP

By Alex Spillius in Washington

8:26PM GMT 19 Nov 2009

Thirty-five years after Nixon was forced to become the only US president to resign, government investigators remain determined to find out the extent of knowledge of the raid on the Democratic National Committee's offices in Washington.

Investigators appointed by the US National Archives are to analyse notes taken by the White House chief of staff HR Haldeman at a meeting with the late president just three days after Nixon campaign members were arrested for breaking into the Watergate building.

Their mission is to find out what Nixon and Haldeman discussed during the 18 ½ minutes missing from tape recordings of the meeting and also from the aide's large yellow note book.

Experts have given up trying to unlock the mystery from the erased tape. The new search will instead scour Haldeman's notes for incriminating clues.

Investigators will use electrostatic detection analysis, which is capable of detecting and highlighting indented images, such as those left on a sheet of paper when a pen has written on a sheet above it. This might show evidence that certain pages were destroyed and even point to words so far lost to history.

Techniques known as hyperspectral imaging and video spectral comparison also will be used to study the ink and look for hidden clues to missing material.

The prospect of confirming that a gap exists in the notes, corresponding with the gap in the recording, has Nixon historians on tenterhooks.

"My best scholarly guess is that Nixon asked Haldeman if anyone in the White House had advance knowledge of the Watergate break-in," said Luke Nichter, a Texas A&M University assistant history professor.